Chapter 4 Functions Of Pid Control; Outline Of Pid Control - Mitsubishi Electric MELSEC-Q series Programming Manual

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FUNCTIONS OF PID CONTROL
This chapter describes PID control performed using the PID control instructions.
4.1

Outline of PID Control

PID control is applicable to process control in which factors such as flowrate, velocity, air flow volume, temperature, tension,
mixing ratio, etc. must be controlled.
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During PID control, the value measured by the sensor (process value) is compared with the preset value (set value). The
output value (manipulated value) is then adjusted in order to eliminate the difference between the process value and the set
value.
The MV (manipulated value) is calculated by combining the proportional operation (P), the integral operation (I), and the
derivative operation (D) so that the PV is brought to the same value as the SV quickly and precisely.
The MV is made large when the difference between the PV and the SV is large so as to bring the PV close to the SV quickly.
As the difference between the PV and the SV gets smaller, a smaller MV is used to bring the PV to the same value as the SV
gradually and accurately.
4 FUNCTIONS OF PID CONTROL
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4.1 Outline of PID Control